Heat exchangers are used for exchanging heat between two fluids. For this purpose heat exchangers usually have tubes, in particular flat tubes, through which one of these fluids flows and around which the other fluid flows. In so-called cross-flow heat exchangers, the first fluid and the second fluid flow transversely to one another and thus allow heat exchange between the fluids via the flat tube.
In order to increase the efficiency of these heat exchangers, it is desirable to improve the degree of heat exchange between the flat tube through which the first fluid flows and the second fluid. For this purpose, for example, heat transfer structures, in particular ribs, arranged between the flat tubes, for example are used.
In order to improve the degree of heat exchange, in particular for a more homogeneous heat exchange between the fluids, DE 10 2007 035 581 A1 proposes to partially block the inlet or the outlet of such flat tubes in a heat exchanger in the area of an inflow or outflow of appurtenant collectors through which the first fluid flows. In DE 10 2004 056 592 A1 it is proposed to provide a bypass device in these collectors which diverts the fluid flowing through the flat tubes and the collectors between neighbouring flat tubes. It is known from DE 197 52 139 A1 to provide flat tubes with two inlets and two outlets each wherein the inlets and the outlets are separated from one another by a beading running in the longitudinal direction.
However these measures leave something to be desired with regard to the efficiency of the appurtenant heat exchangers, in particular with regard to the degree of heat exchange between the flat tube and the second fluid flowing around the flat tube.